"The ATP has put this in the hands of the IOC (International Olympic Committee) and WADA (World Anti-Doping Agency) to make sure that the appropriate things are done," Agassi told reporters at the Pacific Life Open which starts on Friday.
"I believe you should go above and beyond in supporting your players. Assuming there was a cross-contamination, there should definitely be an apology."
On Wednesday, a tribunal appointed by the ATP exonerated Canadian-born Rusedski after he tested positive for nandrolone, saying the ATP itself had probably provided contaminated supplements.
"I can only imagine what it would be like to have your entire life and career on the line," Agassi said.
"That's why it's so important that the due process is fair. They had an investigation that found he should be exonerated.
"From a competitor's standpoint, the players have to count on two things: how extensive our testing is, meaning are we really getting to the bottom of are people cheating, and is there going to be some sort of due process that's fair?
"All we can really do is count on our governing body to see if it is dealt with fairly."
Even though Rusedski tested positive for twice the legal limit of nandrolone, eight times grand slam champion Agassi believes the 1997 U.S. Open runner-up was not trying to get an edge.
'NOT CHEATING'
"In this case and all other cases we've talked about, we are talking about positives that are so minimal they are not even performance enhancing," Agassi said.
"You are talking about an amount of something in your system that's a clear indication of cross-contamination that happens probably in a good portion of the products that you take at the local drug store.
"This isn't about players cheating, it's about something that is showing up in player's systems that isn't even considered performance enhancing. The issue should be dealt with head on."
Even though the ATP anti-doping policy has failed to successfully prosecute in the cases of Rusedski and Czech Bohdan Ulihrach, whose suspension was overturned last year, Agassi said the tour needs to keep vigilant.
"I need to be on the court knowing that if I am playing someone who is trying to enhance their performance illegally, that they are going to get caught."
Agassi was recently named to an ATP task force that is investigating the issues and said that the tour must locate the source of the contamination and approve a set of supplemental products that the players can take.
"We've got guys being scared to drink out of a Gatorade bottle," Agassi said.
"We have to get to the bottom if it. The thought of somebody's livelihood, career or legacy to be ripped to shreds for an accident is a terrible thought."
